1. Field of the Invention
The present invention relates to an imaging apparatus capable of registering feature data of an object for individual authentication, and a method for controlling the apparatus.
2. Description of the Related Art
In these days, there is known an imaging apparatus that provides a function of detecting an object such as a person from a captured image and carrying out an auto-focus (AF) operation for the detected object. Further, there is known an imaging apparatus that can carry out individual authentication for identifying even who the person detected from the image is.
In the imaging apparatus that carries out individual authentication, feature amount data of a person face is registered beforehand in a storage area of a camera, and the individual authentication is executed by collating a feature amount of a face detected during image capturing with the registered feature amount data of the person face. There is provided a function of applying, when the individual authentication is carried out to discover that the detected person matches the registered person, a special effect to the person face or preferentially focusing on the person face.
Japanese Patent Application Laid-Open No. 2010-259088 discusses a method for extracting a feature amount from a face captured by setting a face registration mode of manually registering a face, registering a name, a birthday, and identification priority in association, and carrying out individual authentication (individual identification) by using the registered feature amount of the face.
There has also been offered a method capable of registering a face to be frequently captured without setting a face registration mode by automatically displaying, when a face having the same feature amount not registered is detected several times in an image-capturing mode, a screen for inquiring whether to register the face.
There is known an imaging apparatus that quickly changes to an image-capturing mode when a shutter button is half-pressed not in an image-capturing standby state of the image-capturing mode. Japanese Patent Application Laid-Open No. 2000-165706 discusses an imaging apparatus that carries out control to start an image-capturing operation when a shutter switch 62 is pressed in a displayed state of a menu screen to output a signal SW1 from a switch 62a. 
In the individual authentication function, in order to improve authentication accuracy, it is desirable to register a plurality of feature data for the same object. However, in the method discussed in Japanese Patent Application Laid-Open No. 2010-259088, in the face registration mode, when one feature data is registered, the face registration mode is ended. Thus, the face registration mode must be set again to register the plurality of feature data for the same object.
However, for a user having no knowledge about the desirability of registering the plurality of feature data for the same object, there is no motive for setting the face registration mode again to additionally register the feature data for the same object.
As in the case of a baby changing its face features at it grows into a child, reliability of feature data registered in the past is lowered as information for identifying a current object to be captured due to a change of the objet itself with time. Thus, even when the plurality of feature data has been registered, it is desirable to frequently update the registered feature data. Particularly, there is a demand for a user interface that enables easy updating of the feature data.
In the case of a configuration where, when an object targeted for feature data registration is selected, a registration operation is not received even if the feature data registered in the object has reached an upper limit, the user loses a chance to update the feature data. In other words, even when the registered feature data having reached the upper limit includes old feature data, the registered feature data is not updated unless the user is aware that replacement of the old feature data improves authentication accuracy.
Even when the feature data is replaced, addition is not permitted before the feature data is explicitly deleted from a menu for deleting the feature data to secure the number of remaining registerable feature data. This means time and labor for the user.
As discussed in Japanese Patent Application Laid-Open No, 2000-165706, when the camera changes to an image-capturing standby state according to an operation of the shutter button not in an image-capturing standby state, for example, during displaying of a menu screen, it is suitable because the user trying to carryout image-capturing in the image-capturing mode can quickly carry out the image-capturing. However, the operation of the shutter button carried out in an operation mode for registering the face feature data as in the case of the face registration mode of Japanese Patent Application Laid-Open No. 2010-259088 may possibly be for instructing acquisition of an image including a face to be registered. Thus, image-capturing in the image-capturing mode is not necessarily intended.
As a result, when the camera changes to the image-capturing standby state of the image-capturing mode according to the operation of the shutter button in the face registration mode, work contents carried out thus far to register the face are discarded, thus lowering usability.